TABLE 3. Performance on Behavioral Tasks, Group Differences As Assessed by One-Tailed, Two-Sample t Tests and Correlations Between Behavioral Performance and GABA Concentration.
| Young Adult Group (n = 17) | Older Adult Group (n = 18) | Group Difference | Correlation with GABA (Across All Participants) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | t | p (one-tailed) | R | p (one-tailed) | ||
| Better performance higher | CFMT | 76.32 | 10.83 | 66.34 | 10.92 | 2.98 | <0.001 | 0.15 | 0.20 |
| Contour detection | 43.27 | 7.26 | 36.19 | 4.39 | 3.83 | <0.001 | 0.08 | 0.32 | |
| Digit symbol | 73.57 | 15.20 | 50.29 | 9.38 | 5.98 | <0.001 | 0.16 | 0.18 | |
| Pattern comparison | 22.62 | 3.10 | 14.60 | 2.58 | 9.11 | <0.001 | 0.27 | 0.06 | |
| COWAT | 44.76 | 9.85 | 42.29 | 13.66 | 0.67 | 0.25 | 0.49 | <0.01 | |
| Better performance lower | CFPT upright | 4.22 | 1.11 | 5.62 | 1.94 | −2.86 | <0.001 | −0.29 | <0.05 |
| CFPT inverted | 7.94 | 2.22 | 8.70 | 1.28 | −1.37 | 0.09 | 0.09 | n.s.* | |
| Dot Speed | 23.26 | 10.38 | 28.78 | 11.69 | −1.62 | 0.06 | −0.18 | 0.16 | |
| Dot Coherence | 38.23 | 12.68 | 48.48 | 23.09 | −1.78 | <0.05 | −0.30 | <0.05 | |
| Trail making A | 22.97 | 6.51 | 34.19 | 10.20 | −4.25 | <0.001 | −0.07 | 0.35 | |
| Trail making B | 50.34 | 12.85 | 82.96 | 38.09 | −3.72 | <0.001 | −0.30 | <0.05 | |
CFMT, Cambridge face memory test; CFPT, Cambridge face perception test; COWAT, controlled oral word association test; GABA, gamma-aminobutyric acid.
*
Nonsignificant. Relationship between task performance and GABA levels was opposite to that predicted, and so exact significance values were not calculated.